The present invention relates to modulated semiconductor diodes, and more particularly, to reduced nonlinearity distortion of semiconductor diode light sources.
As optical communication demand increases, so does the need for better quality, lower distortion optical communication technology.
At the heart of optical transmission systems lies the light source. Light-emitting diodes (LEDs) and laser diodes commonly provide light for these systems. The inherently nonlinear junction capacitance of these devices, however, creates undesired harmonics and intermodulation products which introduce distortion, degrading their performance.
High linearity and low noise in the light source are critical factors in optical transmission systems. Others have sought to improve light-source linearity by improving light-source fabrication technology, reducing predistortion, and implementing feedback control. These methods, however, create undesirable high costs and manufacturing difficulties. The present inventor, in a previous invention (U.S. Pat. No. 4,032,802), improved the linearity by using an anti-series connection of diodes to reduce second- and third-order distortion harmonics.
The present invention uses an antiparallel connection of semiconductor diodes, with one diode reverse-biased, to improve upon the inventor's earlier, anti-series configuration distortion-reducing system, to reduce harmonic distortion while also reducing the D.C. power consumption, low-frequency noise, and heat generation, as compared to the anti-series connected system.